Electric Bacteria

I'd been aware that Geobacter could respire on electron flow. But now we learn there's an entire hidden biosphere of electric bacteria. What I don't understand is the claim that they live entirely on electrons, because they're still made of molecules. Surely bacteria can't reproduce without acquiring more matter.

STICK an electrode in the ground, pump electrons down it, and they will come: living cells that eat electricity.

Unlike any other living thing on Earth, electric bacteria use energy in its purest form – naked electricity in the shape of electrons harvested from rocks and metals. We already knew about two types, Shewanella and Geobacter.

Geobacter

Now, biologists are showing that they can entice many more out of rocks and marine mud by tempting them with a bit of electrical juice. Experiments growing bacteria on battery electrodes demonstrate that these novel, mind-boggling forms of life are essentially eating and excreting electricity.

Bugs in the sediments can either "eat" electrons from the higher voltage, or "breathe" electrons on to the lower-voltage electrode, generating a current.

... identified up to eight different kinds of bacteria that consume electricity. ... , all very different to one another, and none of them anything like Shewanella or Geobacter.